This invention relates in general to devices for the transfer and handling of semiconductor wafers or slices and in particular to devices for the bulk transfer and handling of pluralities of semiconductor wafers. Still more particularly, this invention relates to devices for the bulk transfer and handling of pluralities of semiconductor wafers which are suitable for utilization with automated handling systems.
The handling and manufacture of integrated circuit devices is a fast growing area of technical expertise. Since its introduction over twenty years ago the integrated circuit has become more and more commonplace in our everyday lives and the manufacturers of such circuits are continually searching for more efficient methods and apparatus for handling these devices during the various stages of manufacture.
Those skilled in the art of integrated circuit manufacture will appreciate that such devices are generally constructed by planar diffusion techniques on wafers or slices of monocrystalline silicon. These wafers are generally thin slices of pure silicon which are subjected to various diffusion steps, metallization steps and acid etching to create hundreds of identical integrated circuits on a single wafer. Photolithography and other techniques are utilized to ensure that each device on a given slice is identical and after all processing is complete each circuit is cut from the wafer and wire-bonded into a suitable package for utilization in electronic circuitry.
It is toward the more efficient handling of these semiconductor wafers that the present invention is directed, since each wafer represents a large investment in time and effect. Bulk transport of semiconductor wafers generally is accomplished utilizing a container or "boat" which includes a number of vertical slots for storing these disk-shaped semiconductor wafers in an "on-edge" position. These "boats" are standardized throughout the industry and each generally holds twenty-five or fifty wafers when fully loaded. Certain forms of treatment of the semiconductor wafers (specifically heat treatment) require different construction materials for the boat or container and transfer of a large number of wafers to or from different boat types is generally a manual operation and extremely tedious in nature. Additionally, it is common that manual transfer of semiconductor wafers in this manner can result in damage to the wafer or the circuitry disposed thereon. Recently, devices have been manufactured which will remove a plurality of semiconductor wafers from a boat and place those wafers in temporary storage for transfer to a second boat; however, these devices utilize manual latches or retainers to ensure that the semiconductor wafers are properly retained in temporary storage. The utilization of a manual operation such as a latch will occasionally result in an accident due to human error which may damage a large number or semiconductor wafers.